Not applicable.
Not applicable.
The present invention relates to fumigant structures that are ignited to dispense desired volatile actives.
The term xe2x80x9cfumigantxe2x80x9d herein means a burnable material that releases a volatile ingredient as the material burns, and preferably as it slowly smolders. A xe2x80x9cvolatile materialxe2x80x9d or xe2x80x9cvolatile ingredient,xe2x80x9d in that context, burning fumigant including, by way of example only, fragrances, disinfectants, and insect control actives. The term xe2x80x9cactivexe2x80x9d refers to a volatile material to be released in order to achieve the desired effect of the fumigant. For a fumigant intended to repel mosquitoes, for example, an insect repellant would be an xe2x80x9cactive.xe2x80x9d An xe2x80x9cinsect control activexe2x80x9d or xe2x80x9cinsect control ingredientxe2x80x9d is an active that repels, kills, or desirably modifies the behavior of insects. xe2x80x9cInsectsxe2x80x9d herein means actual insects, as well as other small animals commonly controlled in conjunction with insects, such as spiders and the like.
The fact that a combustible material may be ignited, so as to then disperse an active, vaporizable ingredient as it continues to smolder, is well known. Incense sticks and mosquito coils are examples of such structures. See e.g. U.S. Pat. Nos. 4,959,925 and 5,657,574. The disclosure of these publications and of all other publications referred to herein are incorporated by reference as if fully set forth herein.
While these types of fumigants are fairly inexpensive, they must be used in considerable numbers over the period of a month, for example, if they are a person""s primary means of controlling mosquitoes in sleeping rooms or other living areas, as is common in many parts of the world. One fumigant per night becomes a significant cost for users, especially because these devices are most often used in countries in which annual income levels are very low. In order to make such products widely available in those markets, they must be as inexpensive as possible. In some areas, affordable availability of this type of insect control is particularly important in controlling the spread of malaria and other insect-transmitted diseases.
Traditional, folk remedy approaches to mosquito control include burning widely available, very inexpensive, smoke-producing materials that are used without any insecticide. However, efforts to control mosquitoes by burning materials of this type, such as cow dung or moist leaves, are not very effective and can have other undesirable characteristics, such as excessive odor.
It has also been proposed to use jute rope that has been impregnated with a mosquito repellant as a fumigant. See M. Ansari et al., 31 Indian J. Malariology 57-64 (1994); M. Ansari et al., 29 Indian J. Malariology 203-210 (1992); and V. Sharma et al., 26 Indian J. Malariology 179-185 (1989). This approach shows some promise. However, as with conventional mosquito coils, if the full length of the rope is not needed at a given time, a user must either extinguish the rope or cut it up into smaller lengths. It is common, for example, to burn a fumigant only for the beginning hours of a night. This can require that a user get up in the middle of the night to extinguish a full, normal-sized fumigant so as to reduce the cost of its use.
Thus, there is still a need for improved fumigants, particularly ones that can provide a user with the ability to meter the duration of treatment.
In one aspect, the invention provides a fumigant element that includes a burnable, elongated body that holds an active to be volatilized by burning of the fumigant element. The body has a first connector at one end and a second connector at a location remote from the first connector. The shapes of the first and second connectors are such that a user can connect or join the first connector of a first body with the second connector of a second body in touching relation such that, when one of the bodies is ignited, the other body will be automatically ignited as the first ignited body burns down to the point at which the two bodies are connected. Various connections between the bodies are possible. By way of example only, these include tongue and groove, tapered projection/tapered recess, and log cabin-type horizontal linkages. Preferably the body is rigid and, also preferably, it is made of compacted plant material. By way of example only, compacted wood powder is a suitable compacted plant material. Most preferably, at least one of the first and second connectors is treated with an igniter material.
A user can assemble a segmented but functionally continuous fumigant by joining or connecting successively as many of the fumigant elements as are necessary to create a segmented fumigant (as discussed, below) that will burn for the desired length of time. For a given use period, a user can join one, two, or more of such bodies for use, thereby adjusting the length of the time over which active is released, as well as its total amount, optimizing fumigant usage and controlling cost.
In a preferred embodiment suitable for controlling insects, the active to be volatilized is an insect control active, preferably selected from among pyrethrum, one or more pyrethroids, and combinations thereof.
As already mentioned, the fumigant elements can be assembled into a segmented fumigant. In another aspect, then, the invention provides a segmented fumigant that includes at least first and second burnable, elongated bodies. Each body holds an active to be volatilized by burning of the body, and each body has a first connector at one end and a second connector at a location remote from the first connector. The first connector of a first one of the bodies is so connected in touching relation to the second connector of a second body that the second body is automatically ignited as the first body burns from a location that is remote from its point of connection to the second body to the end of the first body at which it is connected to the second body. Preferably at least one of the connected first and second connectors of the first and second bodies is treated with an igniter material, which aids in the smooth transfer of burning from the first to the second body.
Preferably, the first and second connectors of successive, connected, individual fumigant elements are frictionally engaged or mechanically interlocked. More preferably, they are frictionally engaged, mechanically interlocked, or otherwise so engaged so securely that, when the segmented fumigant is resting on a supporting surface, the first and second bodies (and any additional attached bodies) are sufficiently engaged that the segmented fumigant remains intact when in a position convenient for burning, without requiring external support above the supporting surface.
In an alternative embodiment of the segmented fumigant of the invention, the active of the first body is different from the active of the second body. By that means, a single, segmented fumigant can deliver two or more actives in succession. When the actives are fragrances, for example, successive, different fragrances can be delivered. Without limitation, a second body entirely free of an active also will be understood as having an active different from the active of the first body, making possible, by way of example only, the delivery of bursts of active, separated in time.
The invention further provides a method of dispensing volatile actives that includes the following steps. The first step is to provide at least two fumigant elements, as described above, each fumigant element including a burnable, elongated body holding an active to be volatilized by burning of the fumigant element, the body having a first connector at one end and a second connector at a location remote from the first connector, the shapes of the first and second connectors being such that a user can connect the first connector of a first body with the second connector of a second body in touching relation such that the second body will be automatically ignited as the first body burns down to its first connector.
Then the first connector of a first fumigant element is connected to the second connector of a second fumigant element to join the two fumigant elements. Then one of the connected fumigant elements is ignited at a location distant from its point of connection with the other fumigant element and is allowed to burn. The steps of connecting and igniting can be performed in reverse order, at the preference of any given user. The fumigant elements can be assembled into many different possible geometric arrays. In a preferred arrangement, the fumigant elements are vertically stacked, one on top of the other.
In a preferred embodiment of the method of the invention, the active held by at least one of the fumigant elements provided in the first step, above, is an insect control active, although fragrances or any other active may be used in addition to or instead of an insect control active. In another embodiment, at least two fumigant elements hold differing actives. A preferred base material for forming the bodies is compacted sawdust, as an example of compacted plant material. In one especially preferred form, at least one end of one of the bodies is treated with an igniter material, such as an alkali metal nitrate, sodium or potassium nitrate being preferred. The igniter material can facilitate lighting a first body and also ensure a smooth burning transition between successive bodies in a multi-body fumigant. Various connections between the bodies are possible. By way of example only, these include tongue and groove, tenon and mortise, tapered projection/tapered recess, and log cabin-type horizontal linkages.
In another aspect, the invention provides a kit for forming a burnable fumigant. The kit includes a first compact mass of material in the form of an elongated first body having a first connector. There is also a second compact mass of material in the form of an elongated second body having a second connector. A volatilizable active is held by the first and second bodies, whether on a surface of, impregnated in, or otherwise borne by the bodies. Preferred actives are insect control ingredients and fragrances. When the first connector of the first body is connected to the second connector of the second body, a segmented but functionally continuous fumigant is formed. In some preferred forms, the elongated bodies are between 3 and 10 cm in length. A preferred width of the bodies is between 5 mm and 15 mm.
A wide variety of actives are suitable for use with the present invention. Pyrethrum and pyrethroid type materials commonly now used in mosquito coils are likely to be most useful. Preferred pyrethroids (from the standpoint of expense, activity, or both vis a vis mosquitoes) are d-allethrin, allethrin, prallethrin, bioallethrin, s-bioallethrin, esbiol, dichlorvos, transfluthrin, pyrethrum, and combinations thereof. Other insect control ingredients can also be used, such as the repellents DEET, citronella, lemon grass oil, lavender oil, cinnamon oil, neem oil, clove oil, sandalwood oil, and geraniol, and the insect growth regulators such as hydroprene.
Volatilizable fragrances, such as those typically used in incense sticks, can be used instead of or in addition to an insect control active. A wide variety of such volatile fragrances are well known to those skilled in the art.
These and still other features and advantages of the present invention will be apparent from the description of the preferred embodiments which follows. The following embodiments are merely preferred embodiments. The claims should be looked to in order to judge the full scope of the invention.